Zoom optical system, optical apparatus and imaging apparatus using the zoom optical system, and method for manufacturing the zoom optical system

ABSTRACT

A zoom optical system (ZL) comprises, in order from an object: a first lens group (G 1 ) having a positive refractive power; a second lens group (G 2 ) having a negative refractive power; a third lens group (G 3 ) having a positive refractive power; and a subsequent lens group (GR), wherein upon zooming, a distance between the first lens group (G 1 ) and the second lens group (G 2 ) changes, a distance between the second lens group (G 2 ) and the third lens group (G 3 ) changes, and a distance between the third lens group (G 3 ) and the subsequent lens group (GR) changes, the subsequent lens group (GR) comprises a focusing lens group that moves upon focusing, and the second lens group (G 2 ) comprises a partial group that satisfies following conditional expressions, 1.40&lt;fvr/f2&lt;2.30, 1.80&lt;f1/fw&lt;3.50 where fvr: a focal length of the partial group, f2: a focal length of the second lens group (G 2 ), f1: a focal length of the first lens group (G 1 ), and fw: a focal length of the zoom optical system (ZL) in a wide-angle end state.

TECHNICAL FIELD

The present invention relates to a zoom optical system, an opticalapparatus and an imaging apparatus including the same, and a method formanufacturing the zoom optical system.

TECHNICAL BACKGROUND

Conventionally, zoom optical systems suitable for photographic cameras,electronic still cameras, video cameras and the like have been proposed(for example, see Patent literature 1). Unfortunately, the conventionalzoom optical systems have insufficient optical performances.

PRIOR ARTS LIST Patent Document

Patent literature 1: Japanese Laid-Open Patent Publication No.H04-293007(A)

SUMMARY OF THE INVENTION

A zoom optical system according to a first aspect comprises, in orderfrom an object: a first lens group having a positive refractive power; asecond lens group having a negative refractive power; a third lens grouphaving a positive refractive power; and a subsequent lens group, whereinupon zooming, a distance between the first lens group and the secondlens group changes, a distance between the second lens group and thethird lens group changes, and a distance between the third lens groupand the subsequent lens group changes, the subsequent lens groupcomprises a focusing lens group that moves upon focusing, and the secondlens group comprises a partial group that satisfies followingconditional expressions,1.40<fvr/f2<2.301.80<f1/fw<3.50

where fvr: a focal length of the partial group,

f2: a focal length of the second lens group,

f1: a focal length of the first lens group, and

fw: a focal length of the zoom optical system in a wide-angle end state.

An optical apparatus according to a second aspect comprises the zoomoptical system.

An imaging apparatus according to a third aspect comprises: the zoomoptical system; and an imaging unit that takes an image formed by thezoom optical system.

A method for manufacturing a zoom optical system according to a fourthaspect is a method for manufacturing a zoom optical system comprising,in order from an object: a first lens group having a positive refractivepower; a second lens group having a negative refractive power; a thirdlens group having a positive refractive power; and a subsequent lensgroup, wherein upon zooming, a distance between the first lens group andthe second lens group changes, a distance between the second lens groupand the third lens group changes, and a distance between the third lensgroup and the subsequent lens group changes, the subsequent lens groupcomprises a focusing lens group that moves upon focusing, and each lensis arranged in a lens barrel such that the second lens group comprises apartial group satisfying following conditional expressions,1.40<fvr/f2<2.301.80<f1/fw<3.50

where fvr: a focal length of the partial group,

f2: a focal length of the second lens group,

f1: a focal length of the first lens group, and

fw: a focal length of the zoom optical system in a wide-angle end state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lens configuration of a zoom optical system according toa first example of this embodiment;

FIG. 2A is graphs showing various aberrations of the zoom optical systemaccording to the first example upon focusing on infinity in thewide-angle end state, and FIG. 2B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 3 is graphs showing various aberrations of the zoom optical systemaccording to the first example upon focusing on infinity in theintermediate focal length state;

FIG. 4A is graphs showing various aberrations of the zoom optical systemaccording to the first example upon focusing on infinity in thetelephoto end state, and FIG. 4B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 5A, 5B and 5C are graphs showing various aberrations of the zoomoptical system according to the first example upon focusing on a shortdistant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 6 shows a lens configuration of a zoom optical system according toa second example of this embodiment;

FIG. 7A is graphs showing various aberrations of the zoom optical systemaccording to the second example upon focusing on infinity in thewide-angle end state, and FIG. 7B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 8 is graphs showing various aberrations of the zoom optical systemaccording to the second example upon focusing on infinity in theintermediate focal length state;

FIG. 9A is graphs showing various aberrations of the zoom optical systemaccording to the second example upon focusing on infinity in thetelephoto end state, and FIG. 9B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 10A, 10B and 10C are graphs showing various aberrations of thezoom optical system according to the second example upon focusing on ashort distant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 11 shows a lens configuration of a zoom optical system according toa third example of this embodiment;

FIG. 12A is graphs showing various aberrations of the zoom opticalsystem according to the third example upon focusing on infinity in thewide-angle end state, and FIG. 12B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 13 is graphs showing various aberrations of the zoom optical systemaccording to the third example upon focusing on infinity in theintermediate focal length state;

FIG. 14A is graphs showing various aberrations of the zoom opticalsystem according to the third example upon focusing on infinity in thetelephoto end state, and FIG. 14B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 15A, 15B and 15C are graphs showing various aberrations of thezoom optical system according to the third example upon focusing on ashort distant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 16 shows a lens configuration of a zoom optical system according toa fourth example of this embodiment;

FIG. 17A is graphs showing various aberrations of the zoom opticalsystem according to the fourth example upon focusing on infinity in thewide-angle end state, and FIG. 17B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 18 is graphs showing various aberrations of the zoom optical systemaccording to the fourth example upon focusing on infinity in theintermediate focal length state;

FIG. 19A is graphs showing various aberrations of the zoom opticalsystem according to the fourth example upon focusing on infinity in thetelephoto end state, and FIG. 19B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 20A, 20B and 20C are graphs showing various aberrations of thezoom optical system according to the fourth example upon focusing on ashort distant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 21 shows a lens configuration of a zoom optical system according toa fifth example of this embodiment;

FIG. 22A is graphs showing various aberrations of the zoom opticalsystem according to the fifth example upon focusing on infinity in thewide-angle end state, and FIG. 22B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 23 is graphs showing various aberrations of the zoom optical systemaccording to the fifth example upon focusing on infinity in theintermediate focal length state;

FIG. 24A is graphs showing various aberrations of the zoom opticalsystem according to the fifth example upon focusing on infinity in thetelephoto end state, and FIG. 24B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 25A, 25B and 25C are graphs showing various aberrations of thezoom optical system according to the fifth example upon focusing on ashort distant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 26 shows a lens configuration of a zoom optical system according toa sixth example of this embodiment;

FIG. 27A is graphs showing various aberrations of the zoom opticalsystem according to the sixth example upon focusing on infinity in thewide-angle end state, and FIG. 27B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.30°;

FIG. 28 is graphs showing various aberrations of the zoom optical systemaccording to the sixth example upon focusing on infinity in theintermediate focal length state;

FIG. 29A is graphs showing various aberrations of the zoom opticalsystem according to the sixth example upon focusing on infinity in thetelephoto end state, and FIG. 29B is graphs showing meridional lateralaberrations when blur correction is applied to a rotational blur by0.20°;

FIGS. 30A, 30B and 30C are graphs showing various aberrations of thezoom optical system according to the sixth example upon focusing on ashort distant object in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively;

FIG. 31 shows a configuration of a camera including the zoom opticalsystem according to this embodiment; and

FIG. 32 is a flowchart showing a method for manufacturing the zoomoptical system according to this embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a zoom optical system, an optical apparatus, and an imagingapparatus according to this embodiment are described with reference tothe drawings. As shown in FIG. 1, a zoom optical system ZL(1) as anexample of the zoom optical system (zoom lens) ZL according to thisembodiment comprises, in order from an object: a first lens group G1having a positive refractive power; a second lens group G2 having anegative refractive power; a third lens group G3 having a positiverefractive power; and a subsequent lens group GR (a fourth lens group G4and a fifth lens group G5) consisting of at least one lens group. Uponzooming, a distance between the first lens group G1 and the second lensgroup G2 changes, a distance between the second lens group G2 and thethird lens group G3 changes, and a distance between the third lens groupG3 and the subsequent lens group GR changes. The subsequent lens groupGR comprises a focusing lens group that moves upon focusing.

The zoom optical system ZL according to this embodiment may be a zoomoptical system ZL(2) shown in FIG. 6, may be a zoom optical system ZL(3)shown in FIG. 11, may be a zoom optical system ZL(4) shown in FIG. 16,may be a zoom optical system ZL(5) shown in FIG. 21, and may be a zoomoptical system ZL(6) shown in FIG. 26. The groups in the zoom opticalsystems ZL(2), ZL(3), ZL(5) and ZL(6) respectively shown in FIGS. 6, 11,21 and 26 each have a configuration analogous to that of the zoomoptical system ZL(1) shown in FIG. 1. In the zoom optical system ZL(4)shown in FIG. 16, the subsequent lens group GR consists of a fourth lensgroup G4.

The zoom optical system ZL of this embodiment comprises at least fourlens groups, and changes the distances between lens groups upon zooming,thereby allowing favorable aberration correction upon zooming to befacilitated. Furthermore, the arrangement of the focusing lens group inthe subsequent lens group GR can reduce the size and weight of thefocusing lens group.

With the configuration described above, in the zoom optical system ZLaccording to this embodiment, the second lens group G2 comprises apartial group that satisfies following conditional expressions.1.40<fvr/f2<2.30  (1)1.80<f1/fw<3.50  (2)

where fvr: a focal length of the partial group,

f2: a focal length of the second lens group G2,

f1: a focal length of the first lens group G1, and

fw: a focal length of the zoom optical system ZL in a wide-angle endstate.

The conditional expression (1) defines the appropriate range for theratio of the focal length of the partial group (of the second lens groupG2) to the focal length of the second lens group G2. By satisfying theconditional expression (1), degradation in performance upon blurcorrection can be effectively suppressed. Furthermore, variation invarious aberrations including the spherical aberration upon zooming fromthe wide-angle end state to the telephoto end state can be suppressed.

If the corresponding value of the conditional expression (1) exceeds theupper limit value, the refractive power of the second lens group G2becomes strong, and it is difficult to suppress variation in variousaberrations including the spherical aberration upon zooming. Setting ofthe upper limit value of the conditional expression (1) to 2.20 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (1) to 2.10.

If the corresponding value of the conditional expression (1) falls belowthe lower limit value, the refractive power of the partial group becomesstrong, and it becomes difficult to correct the decentering comaaberration caused upon blur correction. Setting of the lower limit valueof the conditional expression (1) to 1.50 can more securely achieve theadvantageous effects of this embodiment. To further secure theadvantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (1) to 1.60.

The conditional expression (2) defines the appropriate range of theratio of the focal length of the first lens group G1 to the focal lengthof the zoom optical system ZL in the wide-angle end state. By satisfyingthe conditional expression (2), the size of the lens barrel can beprevented from increasing, and variation in various aberrationsincluding the spherical aberration upon zooming from the wide-angle endstate to the telephoto end state can be suppressed.

If the corresponding value of the conditional expression (2) exceeds theupper limit value, the refractive power of the first lens group G1becomes weak, and the size of lens barrel increases. Setting of theupper limit value of the conditional expression (2) to 3.30 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (2) to 3.10.

If the corresponding value of the conditional expression (2) falls belowthe lower limit value, the refractive power of the first lens group G1becomes strong, and it is difficult to correct various aberrationsincluding the spherical aberration upon zooming. Setting of the lowerlimit value of the conditional expression (2) to 1.90 can more securelyachieve the advantageous effects of this embodiment. To further securethe advantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (2) to 2.00, and it ismore preferable to set the lower limit value of the conditionalexpression (2) to 2.10.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (3),3.70<f1/(−f2)<5.00  (3)

The conditional expression (3) defines the appropriate range for theratio of the focal length of the first lens group G1 to the focal lengthof the second lens group G2. By satisfying the conditional expression(3), variation in various aberrations including the spherical aberrationupon zooming from the wide-angle end state to the telephoto end statecan be suppressed.

If the corresponding value of the conditional expression (3) exceeds theupper limit value, the refractive power of the second lens group G2becomes strong, and it is difficult to suppress variation in variousaberrations including the spherical aberration upon zooming. Setting ofthe upper limit value of the conditional expression (3) to 4.90 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (3) to 4.80.

If the corresponding value of the conditional expression (3) falls belowthe lower limit value, the refractive power of the first lens group G1becomes strong, and it is difficult to correct various aberrationsincluding the spherical aberration upon zooming. Setting of the lowerlimit value of the conditional expression (3) to 3.90 can more securelyachieve the advantageous effects of this embodiment. To further securethe advantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (3) to 3.95.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (4),3.20<f1/f3<5.00  (4)

where f3: a focal length of the third lens group G3.

The conditional expression (4) defines the appropriate range for theratio of the focal length of the first lens group G1 to the focal lengthof the third lens group G3. By satisfying the conditional expression(4), variation in various aberrations including the spherical aberrationupon zooming from the wide-angle end state to the telephoto end statecan be suppressed.

If the corresponding value of the conditional expression (4) exceeds theupper limit value, the refractive power of the third lens group G3becomes strong, and it is difficult to suppress variation in variousaberrations including the spherical aberration upon zooming. Setting ofthe upper limit value of the conditional expression (4) to 4.80 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (4) to 4.60.

If the corresponding value of the conditional expression (4) falls belowthe lower limit value, the refractive power of the first lens group G1becomes strong, and it is difficult to correct various aberrationsincluding the spherical aberration upon zooming. Setting of the lowerlimit value of the conditional expression (4) to 3.40 can more securelyachieve the advantageous effects of this embodiment. To further securethe advantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (4) to 3.60.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (5),0.18<(−fF)/f1<0.30  (5)

where fF: a focal length of the focusing lens group.

The conditional expression (5) defines the appropriate range for theratio of the focal length of the focusing lens group to the focal lengthof the first lens group G1. By satisfying the conditional expression(5), variation in various aberrations including the spherical aberrationupon zooming from the wide-angle end state to the telephoto end statecan be suppressed. Furthermore, variation in various aberrationsincluding the spherical aberration upon focusing from the infinitedistant object to the short distant object can be suppressed.

If the corresponding value of the conditional expression (5) exceeds theupper limit value, the refractive power of the first lens group G1becomes strong, and it is difficult to suppress variation in variousaberrations including the spherical aberration upon zooming. Setting ofthe upper limit value of the conditional expression (5) to 0.29 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (5) to 0.28.

If the corresponding value of the conditional expression (5) falls belowthe lower limit value, the refractive power of the focusing lens groupbecomes strong, and it is difficult to correct various aberrationsincluding the spherical aberration upon focusing. Setting of the lowerlimit value of the conditional expression (5) to 0.19 can more securelyachieve the advantageous effects of this embodiment. To further securethe advantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (5) to 0.20.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (6),0.84<(−f2)/f3<1.20  (6)

where f3: a focal length of the third lens group G3.

The conditional expression (6) defines the appropriate range for theratio of the focal length of the second lens group G2 to the focallength of the third lens group G3. By satisfying the conditionalexpression (6), variation in various aberrations including the sphericalaberration upon zooming from the wide-angle end state to the telephotoend state can be suppressed.

If the corresponding value of the conditional expression (6) exceeds theupper limit value, the refractive power of the third lens group G3becomes strong, and it is difficult to suppress variation in variousaberrations including the spherical aberration upon zooming. Setting ofthe upper limit value of the conditional expression (6) to 1.15 can moresecurely achieve the advantageous effects of this embodiment. To furthersecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (6) to 1.10.

If the corresponding value of the conditional expression (6) falls belowthe lower limit value, the refractive power of the second lens group G2becomes strong, and it is difficult to correct various aberrationsincluding the spherical aberration upon zooming. Setting of the lowerlimit value of the conditional expression (6) to 0.87 can more securelyachieve the advantageous effects of this embodiment. To further securethe advantageous effects of this embodiment, it is preferable to set thelower limit value of the conditional expression (6) to 0.90.

In the zoom optical system of this embodiment, preferably, upon zoomingfrom a wide-angle end state to a telephoto end state, the first lensgroup G1 moves toward the object. Accordingly, the entire length of thelens at the wide-angle end state can be reduced, which facilitatesreduction in the size of the zoom optical system.

In the zoom optical system of this embodiment, preferably, the focusinglens group comprises: at least one lens having a positive refractivepower; and at least one lens having a negative refractive power.Accordingly, variation in various aberrations including the sphericalaberration upon focusing from the infinite distant object to the shortdistant object can be suppressed.

In the zoom optical system of this embodiment, preferably, the partialgroup (of the second lens group G2) consists of, in order from theobject: a lens having a negative refractive power; and a lens having apositive refractive power. Accordingly, degradation in performance uponblur correction can be effectively suppressed.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (7),0.80<nN/nP<1.00  (7)

where nN: a refractive index of the lens having the negative refractivepower in the partial group, and

nP: a refractive index of the lens having the positive refractive powerin the partial group.

The conditional expression (7) defines the appropriate range for theratio of the refractive index of the lens that is in the partial group(of the second lens group G2) and has a negative refractive power to therefractive index of the lens that is in the partial group and has apositive refractive power. By satisfying the conditional expression (7),degradation in performance upon blur correction can be effectivelysuppressed.

If the corresponding value of the conditional expression (7) exceeds theupper limit value, the refractive index of the lens that is in thepartial group and has a positive refractive power decreases, and itbecomes difficult to correct the decentering coma aberration caused uponblur correction. Setting of the upper limit value of the conditionalexpression (7) to 0.98 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (7) to 0.96.

If the corresponding value of the conditional expression (7) falls belowthe lower limit value, the refractive index of the lens that is in thepartial group and has a negative refractive power decreases, and itbecomes difficult to correct the decentering coma aberration caused uponblur correction. Setting of the lower limit value of the conditionalexpression (7) to 0.82 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the lower limit value of theconditional expression (7) to 0.84.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (8),1.20<νN/νP<2.40  (8)

where νN: an Abbe number of the lens having the negative refractivepower in the partial group, and

νP: an Abbe number of the lens having the positive refractive power inthe partial group.

The conditional expression (8) defines the appropriate range for theratio of the Abbe number of the lens that is in the partial group (ofthe second lens group G2) and has a negative refractive power to theAbbe number of the lens that is in the partial group and has a positiverefractive power. By satisfying the conditional expression (8),degradation in performance upon blur correction can be effectivelysuppressed.

If the corresponding value of the conditional expression (8) exceeds theupper limit value, the Abbe number of the lens that is in the partialgroup and has a positive refractive power becomes too small, and itbecomes difficult to correct the chromatic aberration caused upon blurcorrection. Setting of the upper limit value of the conditionalexpression (8) to 2.30 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (8) to 2.20.

If the corresponding value of the conditional expression (8) falls belowthe lower limit value, the Abbe number of the lens that is in thepartial group and has a negative refractive power becomes too small, andit becomes difficult to correct the chromatic aberration caused uponblur correction. Setting of the lower limit value of the conditionalexpression (8) to 1.30 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the lower limit value of theconditional expression (8) to 1.40.

In the zoom optical system of this embodiment, preferably, the partialgroup (of the second lens group G2) is a vibration-proof lens groupmovable so as to have a displacement component in a directionperpendicular to an optical axis in order to correct an image blur.Accordingly, degradation in performance upon blur correction can beeffectively suppressed.

In the zoom optical system of this embodiment, preferably, thesubsequent lens group GR comprises: a lens that is disposed to the imageside of the focusing lens group, and has a negative refractive power;and a lens that is disposed to the image side of the lens having thenegative refractive power, and has a positive refractive power.Accordingly, various aberrations including the coma aberration can beeffectively corrected.

It is desirable that the zoom optical system of this embodiment satisfya following conditional expression (9),0.70<(−fN)/fP<2.00  (9)

where fN: a focal length of the lens that is disposed to the image sideof the focusing lens group and has the negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of thelens having the negative refractive power, and has the positiverefractive power.

The conditional expression (9) defines the appropriate range for theratio of the focal length of the lens that is disposed to the image sideof the focusing lens group and has the negative refractive power to thefocal length of the lens that is disposed to the image side of thefocusing lens group (image side of the lens having the negativerefractive power) and has the positive refractive power. By satisfyingthe conditional expression (9), various aberrations including the comaaberration can be effectively corrected.

If the corresponding value of the conditional expression (9) exceeds theupper limit value, the refractive power of the lens that is disposed tothe image side of the focusing lens group and has the positiverefractive power becomes strong, and it becomes difficult to correct thecoma aberration. Setting of the upper limit value of the conditionalexpression (9) to 1.90 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (9) to 1.80.

If the corresponding value of the conditional expression (9) falls belowthe lower limit value, the refractive power of the lens that is disposedto the image side of the focusing lens group and has the negativerefractive power becomes strong, and it becomes difficult to correct thecoma aberration. Setting of the lower limit value of the conditionalexpression (9) to 0.80 can more securely achieve the advantageouseffects of this embodiment. To further secure the advantageous effectsof this embodiment, it is preferable to set the lower limit value of theconditional expression (9) to 0.90.

An optical apparatus and an imaging apparatus according to thisembodiment comprise the zoom optical system having the configurationdescribed above. As a specific example, a camera (corresponding to theimaging apparatus of the invention of the present application) includingthe aforementioned zoom optical system ZL is described with reference toFIG. 31. As shown in FIG. 31, this camera 1 has a lens assemblyconfiguration including a replaceable imaging lens 2. The zoom opticalsystem having the configuration described above is provided in theimaging lens 2. That is, the imaging lens 2 corresponds to the opticalapparatus of the invention of the present application. The camera 1 is adigital camera. Light from an object (subject), not shown, is collectedby the imaging lens 2, and reaches an imaging element 3. Accordingly,the light from the subject is imaged by the imaging element 3, andrecorded as a subject image in a memory, not shown. As described above,a photographer can take an image of the subject through the camera 1.Note that this camera may be a mirrorless camera, or a single-lensreflex type camera including a quick return mirror.

According to the configuration described above, the camera 1 mountedwith the zoom optical system ZL described above in the imaging lens 2can achieve high-speed AF and silence during AF without increasing thesize of the lens barrel by reducing the size and weight of the focusinglens group. Furthermore, variation of aberrations upon zooming from thewide-angle end state to the telephoto end state, and variation ofaberrations upon focusing from an infinite distant object to a shortdistant object can be favorably suppressed, and a favorable opticalperformance can be achieved.

Subsequently, referring to FIG. 32, an overview of a method formanufacturing the aforementioned zoom optical system ZL is described.First, in order from an object, a first lens group G1 having a positiverefractive power, a second lens group G2 having a negative refractivepower, a third lens group G3 having a positive refractive power, and asubsequent lens group GR are arranged (step ST1). Subsequently, it isconfigured such that upon zooming, the distance between the first lensgroup G1 and the second lens group G2 changes, the distance between thesecond lens group G2 and the third lens group G3 changes, and thedistance between the third lens group G3 and the subsequent lens groupGR changes (step ST2). It is also configured such that the subsequentlens group GR comprises the focusing lens group that moves upon focusing(step ST3). Furthermore, each lens is arranged in a lens barrel suchthat the second lens group G2 comprises a partial group satisfying atleast the conditional expressions (1) and (2) (step ST4).

EXAMPLES

Hereinafter, zoom optical systems (zoom lens) ZL according to theexamples of this embodiment are described with reference to thedrawings. FIGS. 1, 6, 11, 16, 21 and 26 are sectional views showing theconfigurations and refractive power distributions of the zoom opticalsystems ZL {ZL(1) to ZL(6)} according to first to sixth examples. Atlower parts of the sectional views of the zoom optical systems ZL(1) toZL(6), the movement direction of each lens group along the optical axisduring zooming from the wide-angle end state (W) to the telephoto endstate (T) is indicated by a corresponding arrow. Furthermore, themovement direction during focusing the focusing lens group from infinityto a short distant object is indicated by an arrow accompanied bycharacters “FOCUSING.”

FIGS. 1, 6, 11, 16, 21 and 26 show each lens group by a combination of asymbol G and a numeral, and show each lens by a combination of a symbolL and a numeral. In this case, to prevent the types and numbers ofsymbols and numerals from increasing and being complicated, the lensgroups and the like are indicated using the combinations of symbols andnumerals independently on an example-by-example basis. Accordingly, eventhough the same combinations of symbols and numerals are used among theexamples, the combinations do not mean the same configurations.

Tables 1 to 6 are shown below. Among these tables, Table 1 is a tablelisting various data in the first example, Table 2 is that in the secondexample, Table 3 is that in the third example, Table 4 is that in thefourth example, Table 5 is that in the fifth example, and Table 6 isthat in the sixth example. In each example, d-line (wavelength λ=587.6nm) and g-line (wavelength λ=435.8 nm) are selected as calculationtargets of aberration characteristics.

In [Lens data] tables, the surface number denotes the order of opticalsurfaces from the object along a light beam traveling direction, Rdenotes the radius of curvature (a surface whose center of curvature isnearer to the image is assumed to have a positive value) of each opticalsurface, D denotes the surface distance, which is the distance on theoptical axis from each optical surface to the next optical surface (orthe image surface), nd denotes the refractive index of the material ofan optical element for the d-line, and νd denotes the Abbe number of thematerial of an optical element with reference to the d-line. The objectsurface denotes the surface of an object. “∞” of the radius of curvatureindicates a flat surface or an aperture. (Stop S) indicates an aperturestop S. The image surface indicates an image surface I. The descriptionof the air refractive index nd=1.00000 is omitted.

In [Various data] tables, f denotes the focal length of the entire zoomlens, FNO denotes the f-number, 2ω denotes the angle of view(represented in units of ° (degree); ω denotes the half angle of view),and Ymax denotes the maximum image height. TL denotes the distanceobtained by adding BF to the distance on the optical axis from the lensforefront surface to the lens last surface upon focusing on infinity. BFdenotes the distance (back focus) on the optical axis from the lens lastsurface to the image surface I upon focusing on infinity. Note thatthese values are represented for zooming states of the wide-angle end(W), the intermediate focal length (M), and the telephoto end (T).

[Variable distance data] tables show the surface distances at surfacenumbers to which the surface distance of “Variable” in the tablerepresenting [Lens data] correspond. This shows the surface distances inthe zooming states of the wide-angle end (W), the intermediate focallength (M) and the telephoto end (T) upon focusing on infinity and ashort distant object.

[Lens group data] tables show the starting surfaces (the surfacesnearest to the object) and the focal lengths of the first to fifth lensgroups (or the fourth lens group).

[Conditional expression corresponding value] tables show valuescorresponding to the conditional expressions (1) to (9) described above.

Hereinafter, for all the data values, the listed focal length f, radiusof curvature R, surface distance D, other lengths and the like aretypically represented in “mm” if not otherwise specified. However, theoptical system can exert equivalent optical performances even if beingproportionally magnified or proportionally reduced. Consequently, therepresentation is not limited thereto.

The above descriptions of the tables are common to all the examples.Hereinafter, redundant description is omitted.

First Example

The first example is described with reference to FIGS. 1 to 5 andTable 1. FIG. 1 shows a lens configuration of a zoom optical systemaccording to the first example of this embodiment. The zoom opticalsystem ZL(1) according to the first example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; a fourth lens group G4having a negative refractive power; and a fifth lens group G5 having apositive refractive power. Upon zooming from the wide-angle end state(W) to the telephoto end state (T), the first to fifth lens groups G1 toG5 move in the directions indicated by the respective arrows in FIG. 1.In this example, the fourth lens group G4 and the fifth lens group G5constitute the subsequent lens group GR. The sign (+) or (−) assigned toeach lens group symbol indicates the refractive power of thecorresponding lens group. This similarly applies to all the followingexamples.

The first lens group G1 consists of, in order from the object: apositive meniscus lens L11 having a convex surface facing the object;and a positive cemented lens consisting of a negative meniscus lens L12having a convex surface facing the object, and a positive biconvex lensL13.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; apositive biconvex lens L22; a negative biconcave lens L23; and anegative cemented lens consisting of a negative biconcave lens L24, anda positive meniscus lens L25 having a convex surface facing the object.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; a positive cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive biconvex lens L35; and a positive biconvex lens L36.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object;and a negative biconcave lens L42.

The fifth lens group G5 consists of, in order from the object: anegative meniscus lens L51 having a concave surface facing the object;and a positive meniscus lens L52 having a convex surface facing theobject. An image surface I is disposed to the image side of the fifthlens group G5.

In the zoom optical system ZL(1) according to the first example, theentire fourth lens group G4 constitutes the focusing lens group, andfocusing from a long distant object to a short distant object isperformed by moving the entire fourth lens group G4 in the image surfacedirection. In the zoom optical system ZL(1) according to the firstexample, the negative cemented lens, which consists of the negative lensL24 and the positive meniscus lens L25 of the second lens group G2,constitutes the vibration-proof lens group (partial group) movable in adirection perpendicular to the optical axis, and corrects the imagingposition displacement (image blur on the image surface I) due to acamera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the first example, the vibration proofcoefficient is 0.97, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.39 mm. In the telephoto end state in thefirst example, the vibration proof coefficient is 2.01, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.51mm.

The following Table 1 lists the values of data on the optical systemaccording to the first example.

TABLE 1 [Lens data] Surface No. R D nd νd Object ∞ surface 1 121.10944.980 1.48749 70.31 2 474.6427 0.200 3 104.9110 1.700 1.83400 37.18 463.9583 9.069 1.49700 81.73 5 −1816.1542 Variable 6 153.9285 1.0001.83400 37.18 7 37.0130 9.180 8 41.8122 5.321 1.80518 25.45 9 −148.00871.552 10 −153.0936 1.000 1.90366 31.27 11 74.4958 4.888 12 −65.07021.000 1.69680 55.52 13 35.9839 3.310 1.83400 37.18 14 121.5659 Variable15 85.1793 3.534 1.80400 46.60 16 −101.3301 0.200 17 38.9890 5.0331.49700 81.73 18 −62.2191 1.200 1.95000 29.37 19 378.6744 1.198 20 ∞19.885 (Stop S) 21 44.8832 1.200 1.85026 32.35 22 20.5002 4.485 1.5168063.88 23 −586.4581 0.200 24 64.4878 2.563 1.62004 36.40 25 −357.2881Variable 26 −801.6030 2.383 1.80518 25.45 27 −50.3151 1.298 28 −57.18731.000 1.77250 49.62 29 26.1668 Variable 30 −21.0000 1.300 1.77250 49.6231 −28.8136 0.200 32 58.9647 3.137 1.62004 36.40 33 524.5289 BF Image ∞surface [Various data] Zooming ratio 4.05 W M T f 72.1 99.9 292.0 FNO4.57 4.79 5.88 2ω 33.24 23.82 8.24 Ymax 21.60 21.60 21.60 TL 191.32204.14 241.16 BF 38.52 42.04 60.52 [Variable distance data] W M T W M TShort Short Short Infinity Infinity Infinity distance distance distanced5 2.000 22.163 69.630 2.000 22.163 69.630 d14 41.783 30.929 2.00041.783 30.929 2.000 d25 2.000 3.259 2.000 2.462 3.867 3.166 d29 14.99913.740 14.999 14.538 13.133 13.833 [Lens group data] Starting FocalGroup surface Length G1 1 167.635 G2 6 −39.933 G3 15 37.727 G4 26−36.765 G5 30 2825.740 [Conditional expression corresponding value]Conditional Expression (1) fvr/f2 = 1.807 Conditional Expression (2)f1/fw = 2.325 Conditional Expression (3) f1/(−f2) = 4.198 ConditionalExpression (4) f1/f3 = 4.443 Conditional Expression (5) (−fF)/f1 = 0.219Conditional Expression (6) (−f2)/f3 = 1.058 Conditional Expression (7)nN/nP = 0.925 Conditional Expression (8) νN/νP = 1.493 ConditionalExpression (9) (−fN)/fP = 1.011

FIGS. 2A and 2B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the firstexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 3 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the first example upon focusing oninfinity in the intermediate focal length state. FIGS. 4A and 4B aregraphs showing various aberrations of the zoom optical system having avibration-proof function according to the first example upon focusing oninfinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 5A, 5B and 5C are graphs showing variousaberrations of the zoom optical system according to the first exampleupon focusing on a short distant object in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

In the aberration graphs of FIGS. 2 to 5, FNO denotes the f-number, NAdenotes the numerical aperture, and Y denotes the image height. Notethat the spherical aberration graph shows the value of the f-number orthe numerical aperture corresponding to the maximum aperture. Theastigmatism graph and the distortion graph show the maximum value of theimage height. The coma aberration graph shows the value of each imageheight. d denotes the d-line (wavelength λ=587.6 nm), and g denotes theg-line (wavelength λ=435.8 nm). In the astigmatism graph, solid linesindicate sagittal image surfaces, and broken lines indicate meridionalimage surfaces. Note that symbols analogous to those in this example areused also in the aberration graphs in the following embodiments.Redundant description is omitted.

The graphs showing various aberrations show that the zoom optical systemaccording to first example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

Second Example

The second example is described with reference to FIGS. 6 to 10 andTable 2. FIG. 6 shows a lens configuration of a zoom optical systemaccording to the second example of this embodiment. The zoom opticalsystem ZL(2) according to the second example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; a fourth lens group G4having a negative refractive power; and a fifth lens group G5 having anegative refractive power. Upon zooming from the wide-angle end state(W) to the telephoto end state (T), the first to fifth lens groups G1 toG5 move in the directions indicated by the respective arrows in FIG. 6.In this example, the fourth lens group G4 and the fifth lens group G5constitute the subsequent lens group GR.

The first lens group G1 consists of, in order from the object: apositive meniscus lens L11 having a convex surface facing the object;and a positive cemented lens consisting of a negative meniscus lens L12having a convex surface facing the object, and a positive biconvex lensL13.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; apositive cemented lens consisting of a positive biconvex lens L22 and anegative biconcave lens L23; and a negative cemented lens consisting ofa negative biconcave lens L24, and a positive meniscus lens L25 having aconvex surface facing the object.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; a negative cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive meniscus lens L35 having a convex surface facing the object;and a positive biconvex lens L36.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object;and a negative biconcave lens L42.

The fifth lens group G5 consists of, in order from the object: anegative meniscus lens L51 having a concave surface facing the object;and a positive meniscus lens L52 having a convex surface facing theobject. An image surface I is disposed to the image side of the fifthlens group G5.

In the zoom optical system ZL(2) according to the second example, theentire fourth lens group G4 constitutes the focusing lens group, andfocusing from a long distant object to a short distant object isperformed by moving the entire fourth lens group G4 in the image surfacedirection. In the zoom optical system ZL(2) according to the secondexample, the negative cemented lens, which consists of the negative lensL24 and the positive meniscus lens L25 of the second lens group G2,constitutes the vibration-proof lens group (partial group) movable in adirection perpendicular to the optical axis, and corrects the imagingposition displacement (image blur on the image surface I) due to acamera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the second example, the vibration proofcoefficient is 0.93, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.41 mm. In the telephoto end state in thesecond example, the vibration proof coefficient is 1.90, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.54mm.

The following Table 2 lists the values of data on the optical systemaccording to the second example.

TABLE 2 [Lens data] Surface No. R D nd νd Object ∞ surface 1 114.53915.639 1.48749 70.31 2 663.8041 0.200 3 103.9783 1.700 1.83400 37.18 462.4686 8.805 1.49700 81.73 5 −43979.1830 Variable 6 146.6152 1.0001.77250 49.62 7 35.8241 11.693 8 37.5245 4.696 1.68893 31.16 9 −254.68341.000 1.83400 37.18 10 64.6045 5.066 11 −60.5874 1.000 1.56883 56.00 1239.1203 2.952 1.75520 27.57 13 93.1442 Variable 14 92.3597 3.688 1.8040046.60 15 −87.7395 0.200 16 36.8528 5.291 1.49700 81.73 17 −63.3187 1.2001.95000 29.37 18 264.8384 1.289 19 ∞ 19.911 (Stop S) 20 52.0583 1.2001.85026 32.35 21 20.7485 3.983 1.51680 63.88 22 439.3463 0.200 2364.0215 2.788 1.62004 36.40 24 −130.2911 Variable 25 −343.5287 2.3711.80518 25.45 26 −47.6881 1.474 27 −51.9782 1.000 1.77250 49.62 2829.6298 Variable 29 −21.0360 1.300 1.60300 65.44 30 −30.1613 0.200 3164.8879 2.981 1.57501 41.51 32 614.9077 BF Image ∞ surface [Variousdata] Zooming ratio 4.05 W M T f 72.1 99.9 292.0 FNO 4.59 4.76 5.87 2ω33.22 23.72 8.22 Ymax 21.60 21.60 21.60 TL 191.32 205.16 240.15 BF 38.5241.03 60.02 [Variable distance data] W M T W M T Short Short ShortInfinity Infinity Infinity distance distance distance d5 2.000 23.30467.717 2.000 23.304 67.717 d13 40.383 30.413 2.000 40.383 30.413 2.000d24 2.000 3.305 2.001 2.487 3.962 3.248 d28 15.588 14.284 15.587 15.10113.626 14.340 [Lens group data] Starting Focal Group surface Length G1 1161.728 G2 6 −38.469 G3 14 38.469 G4 25 −39.083 G5 29 −12107.081[Conditional expression corresponding value] Conditional Expression (1)fvr/f2 = 2.028 Conditional Expression (2) f1/fw = 2.243 ConditionalExpression (3) f1/(−f2) = 4.204 Conditional Expression (4) f1/f3 = 4.204Conditional Expression (5) (−fF)/f1 = 0.242 Conditional Expression (6)(−f2)/f3 = 1.000 Conditional Expression (7) nN/nP = 0.894 ConditionalExpression (8) νN/νP = 2.031 Conditional Expression (9) (−fN)/fP = 0.968

FIGS. 7A and 7B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the secondexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 8 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the second example upon focusingon infinity in the intermediate focal length state. FIGS. 9A and 9B aregraphs showing various aberrations of the zoom optical system having avibration-proof function according to the second example upon focusingon infinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 10A, 10B and 10C are graphs showingvarious aberrations of the zoom optical system according to the secondexample upon focusing on a short distant object in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

The graphs showing various aberrations show that the zoom optical systemaccording to second example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

Third Example

The third example is described with reference to FIGS. 11 to 15 andTable 3. FIG. 11 shows a lens configuration of a zoom optical systemaccording to the third example of this embodiment. The zoom opticalsystem ZL(3) according to the third example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; a fourth lens group G4having a negative refractive power; and a fifth lens group G5 having apositive refractive power. Upon zooming from the wide-angle end state(W) to the telephoto end state (T), the first to fifth lens groups G1 toG5 move in the directions indicated by the respective arrows in FIG. 11.In this example, the fourth lens group G4 and the fifth lens group G5constitute the subsequent lens group GR.

The first lens group G1 consists of, in order from the object: apositive biconvex lens L11; and a positive cemented lens consisting of anegative meniscus lens L12 having a convex surface facing the object,and a positive biconvex lens L13.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; apositive cemented lens consisting of a positive biconvex lens L22 and anegative biconcave lens L23; and a negative cemented lens consisting ofa negative biconcave lens L24, and a positive meniscus lens L25 having aconvex surface facing the object.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; and a positive cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive biconvex lens L35.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object;and a negative biconcave lens L42.

The fifth lens group G5 consists of, in order from the object: anegative meniscus lens L51 having a concave surface facing the object;and a positive biconvex lens L52. An image surface I is disposed to theimage side of the fifth lens group G5.

In the zoom optical system ZL(3) according to the third example, theentire fourth lens group G4 constitutes the focusing lens group, andfocusing from a long distant object to a short distant object isperformed by moving the entire fourth lens group G4 in the image surfacedirection. In the zoom optical system ZL(3) according to the thirdexample, the negative cemented lens, which consists of the negative lensL24 and the positive meniscus lens L25 of the second lens group G2,constitutes the vibration-proof lens group (partial group) movable in adirection perpendicular to the optical axis, and corrects the imagingposition displacement (image blur on the image surface I) due to acamera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the third example, the vibration proofcoefficient is 0.96, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.39 mm. In the telephoto end state in thethird example, the vibration proof coefficient is 2.00, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.51mm.

The following Table 3 lists the values of data on the optical systemaccording to the third example.

TABLE 3 [Lens data] Surface No. R D nd νd Object ∞ surface 1 268.86733.827 1.48749 70.31 2 −1922.6559 0.200 3 111.5860 1.700 1.62004 36.40 461.6123 8.761 1.49700 81.73 5 −1745.4439 Variable 6 124.2629 1.0001.77250 49.62 7 34.3759 7.147 8 35.3149 5.189 1.60342 38.03 9 −190.57751.000 1.77250 49.62 10 75.4448 4.904 11 −65.2960 1.000 1.67003 47.14 1237.2634 3.301 1.80518 25.45 13 119.9726 Variable 14 80.9765 3.9681.77250 49.62 15 −78.4621 0.200 16 33.2120 5.701 1.49700 81.73 17−56.7466 1.200 1.85026 32.35 18 108.8392 1.685 19 ∞ 18.569 (Stop S) 2040.1917 1.200 1.85026 32.35 21 18.3878 4.752 1.54814 45.79 22 −98.0255Variable 23 −121.4042 2.367 1.75520 27.57 24 −36.6433 2.111 25 −37.58951.000 1.77250 49.62 26 35.8631 Variable 27 −21.0000 1.300 1.60311 60.6928 −30.2149 0.200 29 95.7916 3.938 1.67003 47.14 30 −115.9256 BF Image ∞surface [Various data] Zooming ratio 4.05 W M T f 72.1 99.9 292.0 FNO4.61 4.79 5.87 2ω 33.52 23.90 8.28 Ymax 21.60 21.60 21.60 TL 191.32207.98 243.25 BF 38.52 41.37 61.52 [Variable distance data] W M T W M TShort Short Short Infinity Infinity Infinity distance distance distanced5 2.000 25.429 72.273 2.000 25.429 72.273 d13 43.342 33.718 2.00043.342 33.718 2.000 d22 2.000 3.210 3.710 2.512 3.900 5.147 d26 19.23518.025 17.525 18.723 17.335 16.088 [Lens group data] Starting FocalGroup surface Length G1 1 169.647 G2 6 −39.988 G3 14 38.817 G4 23−37.515 G5 27 207.702 [Conditional expression corresponding value]Conditional Expression (1) fvr/f2 = 1.860 Conditional Expression (2)f1/fw = 2.353 Conditional Expression (3) f1/(−f2) = 4.242 ConditionalExpression (4) f1/f3 = 4.370 Conditional Expression (5) (−fF)/f1 = 0.221Conditional Expression (6) (−f2)/f3 = 1.030 Conditional Expression (7)nN/nP = 0.925 Conditional Expression (8) νN/νP = 1.852 ConditionalExpression (9) (−fN)/fP = 1.529

FIGS. 12A and 12B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the thirdexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 13 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the third example upon focusing oninfinity in the intermediate focal length state. FIGS. 14A and 14B aregraphs showing various aberrations of the zoom optical system having avibration-proof function according to the third example upon focusing oninfinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 15A, 15B and 15C are graphs showingvarious aberrations of the zoom optical system according to the thirdexample upon focusing on a short distant object in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

The graphs showing various aberrations show that the zoom optical systemaccording to third example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

Fourth Example

The fourth example is described with reference to FIGS. 16 to 20 andTable 4. FIG. 16 shows a lens configuration of a zoom optical systemaccording to the fourth example of this embodiment. The zoom opticalsystem ZL(4) according to the fourth example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; and a fourth lens group G4having a negative refractive power. Upon zooming from the wide-angle endstate (W) to the telephoto end state (T), the first to fourth lensgroups G1 to G4 move in the directions indicated by the respectivearrows in FIG. 16. In this example, the fourth lens group G4 constitutesthe subsequent lens group GR.

The first lens group G1 consists of, in order from the object: apositive biconvex lens L11; and a positive cemented lens consisting of anegative meniscus lens L12 having a convex surface facing the object,and a positive biconvex L13.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; apositive cemented lens consisting of a positive biconvex lens L22 and anegative biconcave lens L23; and a negative cemented lens consisting ofa negative biconcave lens L24, and a positive meniscus lens L25 having aconvex surface facing the object.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; and a positive cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive biconvex lens L35.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object; anegative biconcave lens L42; a negative meniscus lens L43 having aconcave surface facing the object; and a positive biconvex lens L44. Animage surface I is disposed to the image side of the fourth lens groupG4.

In the zoom optical system ZL(4) according to the fourth example, thepositive meniscus lens L41 and the negative lens L42 in the fourth lensgroup G4 constitute the focusing lens group, and focusing from a longdistant object to a short distant object is performed by moving thepositive meniscus lens L41 and the negative lens L42 in the fourth lensgroup G4 in the image surface direction. In the zoom optical systemZL(4) according to the fourth example, the negative cemented lens, whichconsists of the negative lens L24 and the positive meniscus lens L25 ofthe second lens group G2, constitutes the vibration-proof lens group(partial group) movable in a direction perpendicular to the opticalaxis, and corrects the imaging position displacement (image blur on theimage surface I) due to a camera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the fourth example, the vibration proofcoefficient is 1.05, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.36 mm. In the telephoto end state in thefourth example, the vibration proof coefficient is 2.20, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.46mm.

The following Table 4 lists the values of data on the optical systemaccording to the fourth example.

TABLE 4 [Lens data] Surface No. R D nd νd Object ∞ surface 1 384.88724.307 1.48749 70.31 2 −459.3665 0.200 3 108.5471 1.700 1.62004 36.40 459.1633 8.722 1.49700 81.73 5 −3828.8091 Variable 6 116.0785 1.0001.77250 49.62 7 33.3782 6.789 8 34.8547 5.123 1.64769 33.73 9 −166.23111.000 1.80400 46.60 10 68.6485 5.021 11 −58.3172 1.000 1.66755 41.87 1233.1524 3.543 1.80518 25.45 13 108.5224 Variable 14 80.6236 4.1111.77250 49.62 15 −73.7947 0.200 16 32.8485 5.846 1.49700 81.73 17−53.4390 1.200 1.85026 32.35 18 100.1735 1.748 19 ∞ 17.032 (Stop S) 2045.6071 1.200 1.80100 34.92 21 18.9488 5.048 1.54814 45.79 22 −90.5382Variable 23 −106.0821 2.387 1.72825 28.38 24 −35.2284 2.066 25 −36.88901.000 1.77250 49.62 26 46.9619 Variable 27 −21.5153 1.300 1.60311 60.6928 −31.7338 0.200 29 126.4587 3.612 1.77250 49.62 30 −132.9868 BF Image∞ surface [Various data] Zooming ratio 4.05 W M T f 72.1 99.9 292.0 FNO4.60 4.77 5.88 2ω 33.56 23.82 8.26 Ymax 21.60 21.60 21.60 TL 192.32210.67 244.12 BF 38.52 40.08 57.94 [Variable distance data] W M T W M TShort Short Short Infinity Infinity Infinity distance distance distanced5 2.000 25.713 69.580 2.000 25.713 69.580 d13 40.783 32.701 2.00040.783 32.701 2.000 d22 2.000 3.163 5.584 2.559 3.917 7.234 d26 23.66123.661 23.661 23.103 22.908 22.012 [Lens group data] Starting FocalGroup surface Length G1 1 164.404 G2 6 −37.386 G3 14 38.634 G4 23−61.380 [Conditional expression corresponding value] ConditionalExpression (1) fvr/f2 = 1.802 Conditional Expression (2) f1/fw = 2.280Conditional Expression (3) f1/(−f2) = 4.397 Conditional Expression (4)f1/f3 = 4.255 Conditional Expression (5) (−fF)/f1 = 0.268 ConditionalExpression (6) (−f2)/f3 = 0.968 Conditional Expression (7) nN/nP = 0.924Conditional Expression (8) νN/νP = 1.645 Conditional Expression (9)(−fN)/fP = 1.378

FIGS. 17A and 17B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the fourthexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 18 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the fourth example upon focusingon infinity in the intermediate focal length state. FIGS. 19A and 19Bare graphs showing various aberrations of the zoom optical system havinga vibration-proof function according to the fourth example upon focusingon infinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 20A, 20B and 20C are graphs showingvarious aberrations of the zoom optical system according to the fourthexample upon focusing on a short distant object in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

The graphs showing various aberrations show that the zoom optical systemaccording to fourth example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

Fifth Example

The fifth example is described with reference to FIGS. 21 to 25 andTable 5. FIG. 21 shows a lens configuration of a zoom optical systemaccording to the fifth example of this embodiment. The zoom opticalsystem ZL(5) according to the fifth example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; a fourth lens group G4having a negative refractive power; and a fifth lens group G5 having apositive refractive power. Upon zooming from the wide-angle end state(W) to the telephoto end state (T), the first to fifth lens groups G1 toG5 move in the directions indicated by the respective arrows in FIG. 21.In this example, the fourth lens group G4 and the fifth lens group G5constitute the subsequent lens group GR.

The first lens group G1 consists of, in order from the object: apositive biconvex lens L11; and a positive cemented lens consisting of anegative meniscus lens L12 having a convex surface facing the object,and a positive biconvex lens L13.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; apositive meniscus lens L22 having a convex surface facing the object;and a negative cemented lens consisting of a negative biconcave lensL23, and a positive meniscus lens L24 having a convex surface facing theobject.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; and a positive cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive biconvex lens L35.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object;and a negative biconcave lens L42.

The fifth lens group G5 consists of, in order from the object: anegative meniscus lens L51 having a concave surface facing the object;and a positive biconvex lens L52. An image surface I is disposed to theimage side of the fifth lens group G5.

In the zoom optical system ZL(5) according to the fifth example, theentire fourth lens group G4 constitutes the focusing lens group, andfocusing from a long distant object to a short distant object isperformed by moving the entire fourth lens group G4 in the image surfacedirection. In the zoom optical system ZL(5) according to the fifthexample, the negative cemented lens, which consists of the negative lensL23 and the positive meniscus lens L24 of the second lens group G2,constitutes the vibration-proof lens group (partial group) movable in adirection perpendicular to the optical axis, and corrects the imagingposition displacement (image blur on the image surface I) due to acamera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the fifth example, the vibration proofcoefficient is 1.02, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.37 mm. In the telephoto end state in thefifth example, the vibration proof coefficient is 2.10, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.49mm.

The following Table 5 lists the values of data on the optical systemaccording to the fifth example.

TABLE 5 [Lens data] Surface No. R D nd νd Object ∞ surface 1 494.47633.486 1.48749 70.31 2 −654.7200 0.200 3 104.3848 1.700 1.62004 36.40 460.0944 8.673 1.49700 81.73 5 −2277.9468 Variable 6 131.3496 1.3001.80400 46.60 7 35.6812 7.900 8 36.7192 2.871 1.68893 31.16 9 62.41014.726 10 −66.4912 1.000 1.70000 48.11 11 36.3174 3.414 1.80518 25.45 12127.2974 Variable 13 90.0733 3.862 1.80400 46.60 14 −78.6804 0.200 1533.8033 5.583 1.49700 81.73 16 −57.6791 1.200 1.85026 32.35 17 101.72371.726 18 ∞ 19.598 (Stop S) 19 49.9975 1.200 1.85026 32.35 20 20.10234.713 1.54814 45.79 21 −72.4003 Variable 22 −158.4470 2.458 1.7173629.57 23 −37.7406 1.732 24 −39.9149 1.000 1.77250 49.62 25 43.7406Variable 26 −22.3495 1.300 1.69680 55.52 27 −32.8093 0.200 28 139.76593.301 1.80610 40.97 29 −141.5832 BF Image ∞ surface [Various data]Zooming ratio 4.05 W M T f 72.1 99.9 292.0 FNO 4.68 4.85 5.88 2ω 33.4823.86 8.26 Ymax 21.60 21.60 21.60 TL 192.32 208.96 243.67 BF 38.32 41.0660.32 [Variable distance data] W M T W M T Short Short Short InfinityInfinity Infinity distance distance distance d5 2.000 26.074 74.8342.000 26.074 77.834 d12 45.487 35.318 2.000 45.487 35.318 2.000 d212.000 3.315 2.845 2.597 4.123 4.511 d25 21.171 19.856 20.326 20.57419.048 18.660 [Lens group data] Starting Focal Group surface Length G1 1171.348 G2 6 −41.929 G3 13 40.969 G4 22 −45.959 G5 26 423.598[Conditional expression corresponding value] Conditional Expression (1)fvr/f2 = 1.695 Conditional Expression (2) f1/fw = 2.377 ConditionalExpression (3) f1/(−f2) = 4.087 Conditional Expression (4) f1/f3 = 4.182Conditional Expression (5) (−fF)/f1 = 0.268 Conditional Expression (6)(−f2)/f3 = 1.023 Conditional Expression (7) nN/nP = 0.942 ConditionalExpression (8) νN/νP = 1.890 Conditional Expression (9) (−fN)/fP = 1.209

FIGS. 22A and 22B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the fifthexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 23 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the fifth example upon focusing oninfinity in the intermediate focal length state. FIGS. 24A and 24B aregraphs showing various aberrations of the zoom optical system having avibration-proof function according to the fifth example upon focusing oninfinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 25A, 25B and 25C are graphs showingvarious aberrations of the zoom optical system according to the fifthexample upon focusing on a short distant object in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

The graphs showing various aberrations show that the zoom optical systemaccording to fifth example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

Sixth Example

The sixth example is described with reference to FIGS. 26 to 30 andTable 6. FIG. 26 shows a lens configuration of a zoom optical systemaccording to the sixth example of this embodiment. The zoom opticalsystem ZL(6) according to the sixth example consists of, in order fromthe object: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a positive refractive power; a fourth lens group G4having a negative refractive power; and a fifth lens group G5 having apositive refractive power. Upon zooming from the wide-angle end state(W) to the telephoto end state (T), the first to fifth lens groups G1 toG5 move in the directions indicated by the respective arrows in FIG. 26.In this example, the fourth lens group G4 and the fifth lens group G5constitute the subsequent lens group GR.

The first lens group G1 consists of, in order from the object: apositive cemented lens consisting of a negative meniscus lens L11 havinga convex surface facing the object, and a positive biconvex lens L12;and a positive meniscus lens L13 having a convex surface facing theobject.

The second lens group G2 consists of, in order from the object: apositive biconvex lens L21; a negative biconcave lens L22; a positivemeniscus lens L23 having a convex surface facing the object; and anegative cemented lens consisting of a negative biconcave lens L24, anda positive meniscus lens L25 having a convex surface facing the object.

The third lens group G3 consists of, in order from the object: apositive biconvex lens L31; a positive cemented lens consisting of apositive biconvex lens L32 and a negative biconcave lens L33; anaperture stop S; and a positive cemented lens consisting of a negativemeniscus lens L34 having a convex surface facing the object, and apositive biconvex lens L35.

The fourth lens group G4 consists of, in order from the object: apositive biconvex lens L41; and a negative biconcave lens L42.

The fifth lens group G5 consists of, in order from the object: anegative meniscus lens L51 having a concave surface facing the object;and a positive meniscus lens L52 having a convex surface facing theobject. An image surface I is disposed to the image side of the fifthlens group G5.

In the zoom optical system ZL(6) according to the sixth example, theentire fourth lens group G4 constitutes the focusing lens group, andfocusing from a long distant object to a short distant object isperformed by moving the entire fourth lens group G4 in the image surfacedirection. In the zoom optical system ZL(6) according to the sixthexample, the negative cemented lens, which consists of the negative lensL24 and the positive meniscus lens L25 of the second lens group G2,constitutes the vibration-proof lens group (partial group) movable in adirection perpendicular to the optical axis, and corrects the imagingposition displacement (image blur on the image surface I) due to acamera shake or the like.

Note that to correct a rotational blur with an angle θ at a lens havingthe focal length f of the entire system and a vibration proofcoefficient K (the ratio of the amount of image movement on the imageforming surface to the amount of movement of the movable lens group uponblur correction), the movable lens group for blur correction is moved ina direction orthogonal to the optical axis by (f·tan θ)/K. In thewide-angle end state in the sixth example, the vibration proofcoefficient is 1.01, and the focal length is 72.1 mm. Accordingly, theamount of movement of the vibration-proof lens group to correct arotational blur by 0.30° is 0.37 mm. In the telephoto end state in thesixth example, the vibration proof coefficient is 2.10, and the focallength is 292.0 mm. Accordingly, the amount of movement of thevibration-proof lens group to correct a rotational blur by 0.20° is 0.49mm.

The following Table 6 lists the values of data on the optical systemaccording to the sixth example.

TABLE 6 [Lens data] Surface No. R D nd νd Object ∞ surface 1 139.34081.700 1.64769 33.73 2 77.5654 9.455 1.49700 81.73 3 −496.0322 0.200 4144.5249 3.734 1.48749 70.31 5 357.2933 Variable 6 142.3498 3.3031.84666 23.80 7 −361.0297 1.824 8 −451.3220 1.300 1.83400 37.18 933.3045 7.193 10 35.8308 3.147 1.71736 29.57 11 69.2532 4.718 12−63.1663 1.000 1.66755 41.87 13 34.7105 3.239 1.80518 25.45 14 102.2323Variable 15 73.7312 3.697 1.77250 49.62 16 −95.2978 0.200 17 33.55575.512 1.49700 81.73 18 −68.5312 1.200 1.90366 31.27 19 129.3820 1.534 20∞ 17.193 (Stop S) 21 40.0826 1.200 1.85026 32.35 22 17.3868 5.2681.56732 42.58 23 −141.3282 Variable 24 297.2824 2.624 1.64769 33.73 25−42.2438 0.835 26 −48.9103 1.000 1.77250 49.62 27 31.0082 Variable 28−22.3095 1.300 1.69680 55.52 29 −31.0148 0.200 30 73.8865 3.135 1.8010034.92 31 3043.5154 BF Image ∞ surface [Various data] Zooming ratio 4.05W M T f 72.1 100.0 292.0 FNO 4.65 4.93 5.88 2ω 33.24 23.86 8.28 Ymax21.60 21.60 21.60 TL 192.32 206.35 244.34 BF 38.32 42.77 60.32 [Variabledistance data] W M T W M T Short Short Short Infinity Infinity Infinitydistance distance distance d5 2.000 22.642 74.835 2.000 22.642 74.835d14 44.818 33.757 2.000 44.818 33.757 2.000 d23 2.000 3.329 2.024 2.6044.116 3.661 d27 19.472 18.143 19.448 18.869 17.356 17.812 [Lens groupdata] Starting Focal Group surface Length G1 1 176.000 G2 6 −42.283 G315 38.971 G4 24 −44.470 G5 28 381.600 [Conditional expressioncorresponding value] Conditional Expression (1) fvr/f2 = 1.620Conditional Expression (2) f1/fw = 2.441 Conditional Expression (3)f1/(−f2) = 4.162 Conditional Expression (4) f1/f3 = 4.516 ConditionalExpression (5) (−fF)/f1 = 0.253 Conditional Expression (6) (−f2)/f3 =1.085 Conditional Expression (7) nN/nP = 0.924 Conditional Expression(8) νN/νP = 1.645 Conditional Expression (9) (−fN)/fP = 1.286

FIGS. 27A and 27B are graphs showing various aberrations of the zoomoptical system having a vibration-proof function according to the sixthexample upon focusing on infinity in the wide-angle end state, andgraphs showing meridional lateral aberrations when blur correction isapplied to a rotational blur by 0.30°, respectively. FIG. 28 is graphsshowing various aberrations of the zoom optical system having thevibration-proof function according to the sixth example upon focusing oninfinity in the intermediate focal length state. FIGS. 29A and 29B aregraphs showing various aberrations of the zoom optical system having avibration-proof function according to the sixth example upon focusing oninfinity in the telephoto end state, and graphs showing meridionallateral aberrations when blur correction is applied to a rotational blurby 0.20°, respectively. FIGS. 30A, 30B and 30C are graphs showingvarious aberrations of the zoom optical system according to the sixthexample upon focusing on a short distant object in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

The graphs showing various aberrations show that the zoom optical systemaccording to sixth example favorably corrects the various aberrationsand has excellent image forming performances from the wide-angle endstate to the telephoto end state, and further has excellent imageforming performances also upon focusing on a short distant object.

According to each of the examples described above, reduction in size andweight of the focusing lens group can achieve high-speed AF (auto focus)and silence during AF without increasing the size of the lens barrel,and the zoom optical system can be achieved that favorably suppressesvariation of aberrations upon zooming from the wide-angle end state tothe telephoto end state, and variation of aberrations upon focusing froman infinite distant object to a short distant object.

Here, each of the examples described above represents a specific exampleof the invention of the present application. The invention of thepresent application is not limited thereto.

Note that the following details can be appropriately adopted in a rangewithout impairing the optical performance of the zoom optical system ofthis embodiment.

The four-group configurations and the five-group configurations havebeen described as the numeric examples of the zoom optical systems ofthis embodiment. However, the present application is not limitedthereto. Zoom optical systems having other group configurations (forexample, six-group ones and the like) can also be configured.Specifically, a zoom optical system having a configuration where a lensor a lens group is added to the zoom optical system of this embodimentat a position nearest to the object or to the image surface may beconfigured. Note that the lens group indicates a portion that has atleast one lens and is separated by air distances varying upon zooming.

Note that the focusing lens group indicates a portion that has at leastone lens and is separated by air distances varying upon focusing. Thatis, a focusing lens group may be adopted that achieves focusing from theinfinite distant object to the short distant object by moving one ormore lens groups or the partial lens group in the optical axisdirection. The focusing lens group is applicable also to autofocus, andis suitable also to motor drive for autofocus (using an ultrasonic motoror the like).

In each example of the zoom optical system of this embodiment, theconfiguration having the vibration-proof function is described. However,the present application is not limited thereto. A configuration havingno vibration-proof function can be adopted.

The lens surface may be formed of a spherical surface or a planesurface, or an aspherical surface. A case where the lens surface is aspherical surface or a plane surface facilitates lens processing andassembly adjustment, and can prevent the optical performance from beingreduced owing to the errors in processing or assembly adjustment.Consequently, the case is preferable. It is also preferable becausereduction in depiction performance is small even when the image surfacedeviates.

In a case where the lens surface is an aspherical surface, theaspherical surface may be an aspherical surface made by a grindingprocess, a glass mold aspherical surface made by forming glass into anaspherical shape with a mold, or a composite type aspherical surfacemade by forming resin provided on the glass surface into an asphericalshape. The lens surface may be a diffractive surface. The lens may be agradient index lens (GRIN lens) or a plastic lens.

Preferably, the aperture stop is disposed in the third lens group.Alternatively, a lens frame may replace the role without providing amember serving as the aperture stop.

To reduce flares and ghosts and achieve a high contrast opticalperformance, an antireflection film having a high transmissivity over awide wavelength range may be applied onto each lens surface. Thisreduces flares and ghosts, and can achieve a high optical performancehaving a high contrast.

EXPLANATION OF NUMERALS AND CHARACTERS

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourthlens group G5 Fifth lens group GR Subsequent lens group I Image surfaceS Aperture stop

The invention claimed is:
 1. A zoom optical system comprising, in orderfrom an object: a first lens group having a positive refractive power; asecond lens group having a negative refractive power; a third lens grouphaving a positive refractive power; and a subsequent lens group, whereinupon zooming, a distance between the first lens group and the secondlens group changes, a distance between the second lens group and thethird lens group changes, and a distance between the third lens groupand the subsequent lens group changes, the subsequent lens groupcomprises a focusing lens group that moves upon focusing, and the secondlens group comprises a partial group, the following conditionalexpressions being satisfied,1.40<fvr/f2<2.301.80<f1/fw<3.500.18<(−fF)/f1<0.30 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, fw: a focal length of the zoom optical system in awide-angle end state, and fF: a focal length of the focusing lens group.2. The zoom optical system according to claim 1, wherein a followingconditional expression is satisfied,3.70<f1/(−f2)<5.00.
 3. The zoom optical system according to claim 1,wherein a following conditional expression is satisfied,3.20<f1/f3<5.00 where f3: a focal length of the third lens group.
 4. Thezoom optical system according to claim 1, wherein a followingconditional expression is satisfied,0.84<(−f2)/f3<1.20 where f3: a focal length of the third lens group. 5.The zoom optical system according to claim 1, wherein upon zooming froma wide-angle end state to a telephoto end state, the first lens groupmoves toward the object.
 6. The zoom optical system according to claim1, wherein the focusing lens group comprises: at least one lens havingpositive refractive power; and at least one lens having negativerefractive power.
 7. The zoom optical system according to claim 1,wherein the partial group consists of, in order from the object: a lenshaving a negative refractive power; and a lens having a positiverefractive power.
 8. The zoom optical system according to claim 7,wherein a following conditional expression is satisfied,0.80<nN/nP<1.00 where nN: a refractive index of the lens having thenegative refractive power in the partial group, and nP: a refractiveindex of the lens having the positive refractive power in the partialgroup.
 9. The zoom optical system according to claim 7, wherein afollowing conditional expression is satisfied,1.20<νN/νP<2.40 where νN: an Abbe number of the lens having the negativerefractive power in the partial group, and νP: an Abbe number of thelens having the positive refractive power in the partial group.
 10. Thezoom optical system according to claim 1, wherein the partial group is avibration-proof lens group movable so as to have a displacementcomponent in a direction perpendicular to an optical axis in order tocorrect an image blur.
 11. The zoom optical system according to claim 1,wherein the subsequent lens group comprises: a lens that is disposed tothe image side of the focusing lens group, and has a negative refractivepower; and a lens that is disposed to the image side of the lens havingthe negative refractive power, and has a positive refractive power. 12.The zoom optical system according to claim 11, wherein a followingconditional expression is satisfied,0.70<(−fN)/fP<2.00 where fN: a focal length of the lens that is disposedto the image side of the focusing lens group and has the negativerefractive power, and fP: a focal length of the lens that is disposed tothe image side of the lens having the negative refractive power, and hasthe positive refractive power.
 13. An optical apparatus comprising thezoom optical system according to claim
 1. 14. An imaging apparatuscomprising: the zoom optical system according to claim 1; and an imagingunit that takes an image formed by the zoom optical system.
 15. A methodfor manufacturing a zoom optical system comprising, in order from anobject: a first lens group having a positive refractive power; a secondlens group having a negative refractive power; a third lens group havinga positive refractive power; and a subsequent lens group, wherein themethod comprises one of features A, B, C and D, the feature Acomprising: arranging the the lens groups in a lens barrel such that,upon zooming, a distance between the first lens group and the secondlens group changes, a distance between the second lens group and thethird lens group changes, and a distance between the third lens groupand the subsequent lens group changes, configuring the subsequent lensgroup to include a focusing lens group that moves upon focusing,configuring the second lens group to include a partial group, andsatisfying following conditional expressions,1.40<fvr/f2<2.301.80<f1/fw<3.500.18<(−fF)/f1<0.30 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, fw: a focal length of the zoom optical system in awide-angle end state, and fF: a focal length of the focusing lens group,the feature B comprising: arranging the lens groups in a lens barrelsuch that, upon zooming, a distance between the first lens group and thesecond lens group changes, a distance between the second lens group andthe third lens group and the subsequent lens group changes, configuringthe subsequent lens group to include a focusing lens group that movesupon focusing, configuring the focusing lens group to include: at leastone lens having a positive refractive power; and at least one lenshaving a negative refractive power, configuring the second lens group toinclude a partial group, and satisfying following conditionalexpressions,1.40<fvr/f2<2.301.80<f1/fw<3.500.84<(−f2)/f3<1.20 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, fw: a focal length of the zoom optical system in awide-angle end state, and f3: a focal length of the third lens group,the feature C comprising: arranging the lens groups in a lens barrelsuch that, upon zooming, a distance between the first lens group and thesecond lens group changes, a distance between the second lens group andthe third lens group changes, and a distance between the third lensgroup and the subsequent lens group changes, arranging the lens groupsin the lens barrel such that, upon zooming from a wide-angle end stateto a telephoto end state, the first lens group moves toward the object,configuring the subsequent lens group to include a focusing lens groupthat moves upon focusing, configuring the focusing lens group toinclude: at least one lens having a positive refractive power; and atleast one lens having a negative refractive power, configuring thesecond lens group to include a partial group, and satisfying followingconditional expressions,1.80<f1/fw<3.503.70<f1/(−f2)<5.003.20<f1/f3<5.00 where f2: a focal length of the second lens group, f1: afocal length of the first lens group, f3: a focal length of the thirdlens group, and the feature D comprising: arranging the lens groups in alens barrel such that, upon zooming, a distance between the first lensgroup and the second lens group changes, a distance between the secondlens group and the third lens group changes, and a distance between thethird lens group and the subsequent lens group changes, arranging thelens groups in the lens barrel such that, upon zooming from a wide-angleend state to a telephoto end state, the first lens group moves towardthe object, configuring the subsequent lens group to include a focusinglens group that moves upon focusing, configuring the second lens groupto include a partial group, and satisfying following conditionalexpressions,1.40<fvr/f2<2.303.70<f1/(−f2)<4.80.3.20<f1/f3≤4.255 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, and f3: a focal lenght of the third lens group.
 16. A zoomoptical system comprising, in order from an object: a first lens grouphaving a positive refractive power; a second lens group having anegative refractive power; a third lens group having a positiverefractive power; and a subsequent lens group, wherein upon zooming, adistance between the first lens group and the second lens group changes,a distance between the second lens group and the third lens groupchanges, and a distance between the third lens group and the subsequentlens group changes, the subsequent lens group comprises a focusing lensgroup that moves upon focusing, the focusing lens group comprises: atleast one lens having a positive refractive power; and at least one lenshaving a negative refractive power, and the second lens group comprisesa partial group, the following conditional expressions being satisfied,1.40<fvr/f2<2.301.80<f1/fw<3.500.84<(−f2)/f3<1.20 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, fw: a focal length of the zoom optical system in awide-angle end state, and f3: a focal length of the third lens group.17. A zoom optical system comprising, in order from an object: a firstlens group having a positive refractive power; a second lens grouphaving a negative refractive power; a third lens group having a positiverefractive power; and a subsequent lens group, wherein upon zooming, adistance between the first lens group and the second lens group changes,a distance between the second lens group and the third lens groupchanges, and a distance between the third lens group and the subsequentlens group changes, upon zooming from a wide-angle end state to atelephoto end state, the first lens group moves toward the object, thesubsequent lens group comprises a focusing lens group that moves uponfocusing, the focusing lens group comprises: at least one lens having apositive refractive power; and at least one lens having a negativerefractive power, and the second lens group comprises a partial group,the following conditional expressions being satisfied,1.80<f1/fw<3.503.70<f1/(−f2)<5.003.20<f1/f3<5.00 where f2: a focal length of the second lens group, f1: afocal length of the first lens group, and f3: a focal length of thethird lens group.
 18. A zoom optical system comprising, in order from anobject: a first lens group having a positive refractive power; a secondlens group having a negative refractive power; a third lens group havinga positive refractive power; and a subsequent lens group, wherein uponzooming, a distance between the first lens group and the second lensgroup changes, a distance between the second lens group and the thirdlens group changes, and a distance between the third lens group and thesubsequent lens group changes, upon zooming from a wide-angle end stateto a telephoto end state, the first lens group moves toward the object,the subsequent lens group comprises a focusing lens group that movesupon focusing, and the second lens group comprises a partial group, thefollowing conditional expressions being satisfied,1.40<fvr/f2<2.303.70<f1/(−f2)<4.80.3.20<f1/f3≤4.255 where fvr: a focal length of the partial group, f2: afocal length of the second lens group, f1: a focal length of the firstlens group, and f3: a focal length of the third lens group.